First off, it is very good that you are trying Linux. I hope that you enjoy using it.
Read the following page. It tells you about the pros and cons of each major distribution (Ubuntu, PCLinuxOS, MEPIS Linux, Slackware Linux, Gentoo Linux, FreeBSD, openSUSE, Fedora, Debian GNU/Linux and Mandriva Linux): http://distrowatch.com/dwres.php?resource=major
Here is the infroduction for it: "The bewildering choice and the ever increasing number of Linux distributions can be confusing for those who are new to Linux. This is why this page was created. It lists 10 Linux distributions (plus an honourable mention of FreeBSD, by far the most popular of all of the BSDs), which are generally considered as most widely-used by Linux users around the world. There are no figures to back it up and there are many other distributions that might suit your particular purpose better, but as a general rule, all of these are popular and have very active forums or mailing lists where you can ask questions if you get stuck. Ubuntu, PCLinuxOS and MEPIS Linux are considered the easiest for new users who want to get productive in Linux as soon as possible without having to master all its complexities. On the other end of the spectrum, Slackware Linux, Gentoo Linux and FreeBSD are more advanced distributions that require plenty of learning before they can be used effectively. openSUSE, Fedora, Debian GNU/Linux and Mandriva Linux can be classified as good "middle-road" distributions. KNOPPIX is a live CD (or live DVD); originally very popular as a testing and demonstration tool, although nowadays most major distributions offer a live CD/DVD edition of their products as well. These distributions are loosely listed in order of popularity on DistroWatch, which is NOT an indication of their market share or quality."
If you do decide to go with Ubuntu (which I think is very good) the following link will help you install Ubuntu: http://ubuntuforums.org/showthread.php?t=583007
Here is another link that will help you settle into Linux quite nicely (it is long). It is mainly written for Ubuntu however.
Ubuntu has forums to help you out if you get stuck: http://ubuntuforums.org/
I cannot say what the other distributions offer because I am unsure myself and have not really tried them. The distrowatch page however should give you an unbiased overview of the pros and cons of each distribution.